1. Field of the Application
The present application relates to the field of axial turbomachines, such as jet engines, especially turbofan engines. More particularly, the present application relates to bladed stators in such machines. The bladed stator may be on the compressor, or one of the compressors, or the turbine, or one of the turbines on such a machine.
2. Description of Related Art
Published patent EP 2075412 A1 discloses a device for fixing the stator blades to the shell of a compressor stator stage of an axial turbomachine. Each of the blades includes a fixing platform and an airfoil forming the aerodynamic part of the blade. The shell comprises a groove into which the blade platforms are inserted. The platforms comprise a fixing screw or bolt on their outer face. This screw is intended to pass through the wall of the stator shell and mate up with a nut for clamping the blades. This method of attachment requires assembly and adjustment of each individual blade. It thus needs some time to assemble, in particular for large diameter turbomachines with a large number of blades. In addition, the screws are a considerable weight.
Published patent EP 2339120 A1 discloses another device for fixing the stator blades in the shell of a compressor stator stage of an axial turbomachine. The blades are assembled in sectors on the shell. To do this, the central blades in a sector are inserted radially through a segment of a platform and a segment of an inner shell. The blades at the ends of the sector each comprise a platform at each end in a radial direction, the said platforms being screwed to the stator shell and the inner shell. More specifically, the outer platform of one of these blades is common to two adjacent sectors and provides, through its screws, connection to and fixing of external platform segments. The internal platform ensures the connection between two adjacent inner shell segments. This type of installation requires the manufacture and implementation of a number of parts. Furthermore, the end blades are not identical to the central blades. Furthermore, the stiffness of the fixing is limited given that only the end blades provide a rigid connection to the stator shell. Also the existence of an external platform creates added weight.
Published patent GB 2250782 A discloses another device for fixing the stator blades to a shell of a compressor stator stage of an axial turbomachine. The main blades are formed integrally with an outer shell and an inner shell, these latter comprising slots between the blades for inserting intermediate blades. These intermediate blades can thus be made of a composite material, in contrast to the main blades which are made of metallic material. The aim of this teaching is to facilitate the replacement of damaged blades. However, it requires the use of two types of blades, similar to the previous teaching. In addition, the rigidity of the stator stage may be limited given that only the main blades ensure the rigidity of the inner shell and the auxiliary blades via the said shell.
Although great strides have been made in the area of bladed stators for axial turbomachines, many shortcomings remain.